Batteries comprising a mulitlayer dielectric and sealing film and method of making the batteries

ABSTRACT

A multilayer dielectric and sealing film is disclosed. The multi-layer dielectric sealing film comprises a layer of dielectric material and at least one layer of sealing material. The multilayer film may be positioned between the current collector tabs and the packaging material of a thin film battery to prevent shorting between the tabs and the edge of a metal foil layer in the packaging material. The multi-layer film also provides additional sealant which can flow around and seal around the terminals. By combining the sealing material and the dielectric material into one multi-layer assembly, manufacturing steps can be eliminated.

This application claims the benefit of Provisional U.S. PatentApplication Ser. No. 61/781,514, filed on Mar. 14, 2013, pending, whichis incorporated by reference herein in its entirety.

TECHNICAL FIELD

This application relates to batteries comprising a battery cell, one ormore tabs extending from the battery cell and a packaging materialsealed around the battery cell and to methods of packaging batteries.

BACKGROUND

Thin film battery cell components, such as the anode, cathode andelectrolyte, can be sensitive to exposure to the surrounding externalenvironment (e.g., air, oxygen, carbon monoxide, carbon dioxide,nitrogen, moisture and organic solvents). Protective packaging for thebattery cell is provided to reduce or eliminate exposure of the batterycomponents to the external environment. For example, a multi-layer filmcan be sealed around the periphery of the battery cell to serve asprotective packaging. Thin film batteries can also have one or morecurrent collector tabs protruding from the battery cell to allow forexternal electrical contact with the device being powered. Theseprotruding tabs must necessarily extend through the seal in thepackaging material. However, the tabs protruding through the seal maycompromise the integrity of the seal thereby reducing battery life. Inaddition, the packaging material may include a metal foil layer toreduce the moisture vapor transmission rate of the packaging material.The edge of the metal layer adjacent the tabs can contact the surface ofthe tab thereby creating a short.

Accordingly, there still exists a need for improved methods of packagingthin film batteries having one or more protruding tabs which allow forthe tabs to extend through the seal in the packaging material withoutcompromising the seal or creating a short between the tabs and metalfoil in the packaging material.

SUMMARY

According to a first embodiment, a battery is provided which comprises:

a battery cell having a periphery, the battery cell comprising an anode,a cathode and an electrolyte between the anode and cathode;

an anode tab comprising a first portion in electrical contact with theanode and a second portion extending beyond the periphery of the celland/or a cathode tab comprising a first portion in electrical contactwith the cathode and a second portion extending beyond the periphery ofthe cell;

an upper packaging layer and a lower packaging layer surrounding thebattery cell, wherein the upper and lower packaging layers are sealedtogether to form a seal area around the periphery of the battery celland wherein the anode and/or cathode tabs extend between the upper andlower packaging materials in the seal area; and

a multi-layer dielectric sealing film between the anode and/or cathodetabs and the upper packaging material in the seal area, wherein themulti-layer dielectric sealing film comprises a layer of dielectricmaterial and a first layer of sealing material.

According to a second embodiment, a method of packaging a batterycomprising:

an anode, a cathode and an electrolyte between the anode and cathodeforming a battery cell having a periphery;

an anode tab comprising a first portion in electrical contact with theanode and a second portion extending beyond the periphery of the celland/or a cathode tab comprising a first portion in electrical contactwith the cathode and a second portion extending beyond the periphery ofthe cell;

an upper packaging layer and a lower packaging layer surrounding thebattery cell, wherein the upper and lower packaging layers are sealedtogether to form a seal area around the periphery of the battery celland wherein one or both of the anode and cathode tabs extend between theupper and lower packaging material in the seal area;

wherein the method comprises:

placing a multi-layer dielectric sealing film on the anode tab and/orcathode tab in the seal area, wherein the multi-layer dielectric sealingfilm comprises a layer of dielectric material and a first layer ofsealing material;

sealing the upper and lower packaging materials together, wherein themulti-layer dielectric sealing film is sealed between the anode andcathode tabs and the upper packaging material in the seal area.

The sealing material can be a hot melt adhesive. According to someembodiments, the sealing material comprises a polymer selected from thegroup consisting of acrylics, ethylene acrylic acid (EAA) copolymers,ethylene and ethyl acrylate (EEA) copolymers, ethylene methacrylic acid(EMA) copolymers, ethylene vinyl acetate (EVA) copolymers, polymethylacrylate (PMA), acrylonitrite, vinyl chloride polypropylene (VCPP)copolymers, acrylic nitrile-butadiene-styrene (ABS) copolymers,polyethylene (PE), polypropylene (PP) and mixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a is an exploded view of a battery comprising a multi-layerfilm comprising a sealant layer and a dielectric layer between the anodeand cathode tabs and the upper packaging material.

DETAILED DESCRIPTION

A battery is described which comprises a multilayer film that acts adielectric and sealing film. The film comprises at least one layer of adielectric material and at least one layer of a sealant material.

When sealing a heat sealable pouch it is often necessary to useadditional sealing material in the form of a film or tape. This is oftenrequired to seal around features, such as battery terminals in a thinfilm flexible battery, which must traverse the pouch seal and protrudeoutside of the pouch itself. When the pouch is to have a low moisturetransmission rate (MVTR), a metal film, such as aluminum or copper, isoften used as part of the pouch film. The multi-layer film describedherein can be used to both seal around and electrically isolate anythingthat protrudes from the pouch.

According to some embodiments, the multi-layer film provides electricalinsulation to the battery terminals of a flexible pouch type batterywhile electrically insulating the battery terminals from the metal usedin the pouching foil.

This use of a multi-layer film as described herein eliminates potentialshorting between the battery terminals and the pouching foil in abattery. The multi-layer film also provides additional sealant which canflow around and seal around the terminals. By combining the sealant andthe dielectric into one dielectric sealing tape assembly, manufacturingsteps are eliminated.

According to some embodiments, a thin film of a dielectric material islaminated to, coated with, or otherwise combined with a thin film ofsealing material on one, or both, sides to create a dielectric sealingmaterial. This material is then applied as a sealing tape on the sealarea of a pouch. In the case of a battery, the dielectric film is placedover the battery terminals in such a manner as to provide electricalinsulation between the pouching foil and the battery terminals.

The addition of sealant and dielectric film increases the seal thicknessand may decrease the moisture barrier provided by the seal. Selection ofthin, low MVTR films and sealants can minimize this effect.

FIG. 1 is an exploded view of an embodiment of a battery comprising amulti-layer sealant and dielectric film. As shown in FIG. 1, the batterycomprises an assembled battery cell 801 with two current collector tabs806, 807, having distal ends 811, 813, extending outwardly from itsperiphery. The battery cell is disposed above a lower packaging material800 and below an upper packaging material 808. As shown in FIG. 1,current collector tabs 806, 807 extend outwardly from the periphery ofbattery cell 806 and are substantially flush with the outer edge 803 ofthe lower packaging material 800. Thus, the current collector tabs 806,807 rest on the top of and are supported by the lower packaging material800. FIG. 1 also illustrates a multi-layer sealant and dielectric film817 disposed over the current collector tabs 806, 807. The upperpackaging material 808 extends over the multi-layer sealant anddielectric film 817. The outer edge 815 of the upper packaging material808 is also shown in FIG. 1. As can be seen from FIG. 1, if the upperpackaging material comprises a metal foil layer, the exposed metal onthe outer edge 815 of the upper packaging material 808 may contact thecurrent collector tabs 806, 807 thereby creating a short. In theassembled battery, the multi-layer film 817 would be positioned betweenthe upper packaging material and the upper surfaces of the currentcollector tabs 806, 807 thereby preventing electrical contact betweenthe edge of the metal foil in the upper packaging material 808 and thecurrent collector tabs 806, 807.

A battery having two tabs extending from the cell is shown in FIG. 1.The sealant and dielectric film can also be used with batteries in whichonly one tab extends from the cell. In fact, the sealant and dielectricfilm can be used to seal and electrically isolate any battery featurewhich extends through the seal around the battery cell.

According to some embodiments, the battery comprises an anode layer, acathode layer and an electrolyte layer disposed between the anode andcathode layers. An anode current collector tab for delivering electricalenergy from the battery cell to an external device is attached to andextends outwardly beyond the periphery of the anode layer. A cathodecurrent collector tab is attached to and extends outwardly beyond theperiphery of the cathode. Batteries of this type are described in U.S.patent application Ser. No. 12/466,900, filed on May 15, 2009 andpublished as U.S. Patent Application Publication No. 20090286150 A1,which is incorporated by reference herein in its entirety. Themulti-layer film described herein is used to form a seal around thecathode current collector tab and/or the anode current collector tab.

The anode current collector tab and the cathode current collector can bemade from a conductive web or sheet like material. According to someembodiments, the current collector tabs are composed of metal foils suchas aluminum, copper, or nickel foils. According to some embodiments, thetabs are made from electrodeposited copper or nickel flashed copper. Thecurrent collector tab can be, for example, an electrodeposited coppertab (18 microns). The current collector tabs are desirably thin so thatpackaging materials may be easily sealed around them. For example, thecurrent collector tabs can have a thickness of no more than about 10mils and desirably, no more than about 1 mil (where 1 mil= 1/1000 inchor 0.0254 millimeters). However, current collector tabs having athickness outside of these ranges may also be employed. In someembodiments, the current collector tabs may comprise an extensionprotruding from a larger current collector sheet disposed adjacent ananode or a cathode. According to some embodiments, the tab may comprisea strip of material disposed on, and extending outwardly beyond the edgeof, a current collector sheet, an anode or a cathode.

In a preferred embodiment, the battery cell comprises at least twocurrent collector tabs extending from the battery cell. In a preferredembodiment, the battery cell is substantially planar and substantiallyrectangular, and the current collector tabs extending from the batterycell are substantially planar and substantially rectangular. In apreferred embodiment, the battery comprises a battery cell comprising:(a) an anode, (b) a cathode, (c) an electrolyte disposed between theanode and the cathode; and at least two current collector tabs extendingfrom the battery cell, wherein a first current collector tab is an anodecurrent collector tab extending from the anode, and a second currentcollector tab is a cathode current collector tab extending from thecathode. The cell can be a substantially rectangular, substantiallyplanar cell with two length sides and two width sides wherein thecurrent collector tabs extend from one width side of the cell.Alternatively, the cell can be a substantially rectangular,substantially planar cell with two length sides and two width sides andthe cell comprises at least two current collector tabs extending fromone length side of the cell.

The battery cell can include an electrically insulative and moisture andvapor resistant packaging material surrounding the battery cell. Thepackaging material may be a multilayered packaging material includingone or more sealing layers, one or more electrically insulative layersand one or more moisture and/or vapor barrier layers. For example, theouter packaging material may have a binder adhesive coated on at least aportion of its exterior surface to help bind the battery into anelectronic device, such as a smart card. The binder adhesive isdesirably a heat activated adhesive which activates at temperatures ofat least about 100° C. A binder adhesive may also be applied to at leasta portion of the interior surface of the packaging material to bind theouter packaging material to the battery cell. This interior binderadhesive can have an activation temperature which is lower than theactivation temperature of the exterior binder adhesive.

A single piece of packaging material can be folded over to provide upperand lower packaging materials from a single continuous piece ofmaterial. The fold can be on the side of the battery cell opposite theside from which the current collector tabs extend.

The battery can be a lithium metal or lithium ion battery. The batterycan be a polymer electrolyte battery. The cell can comprise anelectrolyte comprising a soluble polyimide. The electrolyte can be apolymer matrix electrolyte comprising a polyimide, at least one lithiumsalt and at least one solvent. The lithium salt can be present in aconcentration of at least 0.5 moles of lithium per mole of imide ringprovided by the polyimide. The polymer matrix electrolyte can besubstantially optically clear. The anode can comprise a lithium powderand a polymer binder. The polymer binder can be a high temperaturepolymer which is heat-resistant. For example, the polymer binder canhave a glass transition temperature of at least 100° C., or at least150° C. The polymer binder can be selected so that it does not reactwith the lithium powder. According to some embodiments, the polymerbinder is a polyimide. According to some embodiments, the lithium powderhas an average particle size of no more than about 20 microns. Accordingto some embodiments, the cathode comprises a polyimide, an electronicconductive filler and a metal oxide. According to some embodiments, theelectrolyte layer comprises solvent in an amount of about 10 wt. % toabout 50 wt. %, and more particularly, about 15 wt. % to about 40 wt. %,and more particularly, about 20 wt. % to about 30 wt. %. The battery canalso be a metal hydride (e.g., Ni-MH) or nickel-cadmium (Ni—Cd) battery.The battery may have solid, liquid or polymer electrolytes.

Suitable materials that may be used for the various components of thebatteries, including packaging materials, anode and cathode materials,polymer electrolyte materials, and current collector and/or currentcollector tab materials, are described above including, for example, inU.S. Pat. Nos. 5,057,385; 5,326,653; and 6,145,280, each of which isincorporated by reference herein in its entirety.

According to some embodiments, the sealing material comprises a polymerselected from the group consisting of acrylics, ethylene acrylic acid(EAA) copolymers, ethylene and ethyl acrylate (EEA) copolymers, ethylenemethacrylic acid (EMA) copolymers, ethylene vinyl acetate (EVA)copolymers, polymethyl acrylate (PMA), acrylonitrite, vinyl chloridepolypropylene (VCPP) copolymers, acrylic nitrile-butadiene-styrene (ABS)copolymers, polyethylene (PE), polypropylene (PP) and mixtures thereof.

According to some embodiments, the dielectric material comprises apolymer selected from the group consisting of polyester (PET) andpolyetheretherketone (PEEK).

These materials have good heat stability. In addition, PEEK is availablein thin grades, and is much more flexible. According to someembodiments, the dielectric material comprises a polymer selected fromthe group consisting of acrylonitrite (polyacrylonitrile), vinylchloride (PVC) polypropylene copolymers, acrylicnitrile-butadiene-styrene (ABS) copolymers, polyethylene (PE) andpolypropylene (PP).

While the foregoing specification teaches the principles of the presentinvention, with examples provided for the purpose of illustration, itwill be appreciated by one skilled in the art from reading thisdisclosure that various changes in form and detail can be made withoutdeparting from the true scope of the invention.

What is claimed is:
 1. A battery comprising: a battery cell having aperiphery, the battery cell comprising an anode, a cathode and anelectrolyte between the anode and cathode; an anode tab comprising afirst portion in electrical contact with the anode and a second portionextending beyond the periphery of the cell and/or a cathode tabcomprising a first portion in electrical contact with the cathode and asecond portion extending beyond the periphery of the cell; an upperpackaging layer and a lower packaging layer surrounding the batterycell, wherein the upper and lower packaging layers are sealed togetherto form a seal area in a periphery of the battery cell and wherein theanode and/or cathode tabs extend between the upper and lower packagingmaterials in the seal area; and a multi-layer dielectric sealing filmbetween the anode and/or cathode tabs and the upper packaging materialin the seal area, wherein the multi-layer dielectric sealing filmcomprises a layer of dielectric material and a first layer of sealingmaterial.
 2. The battery of claim 1, wherein the upper packagingmaterial comprises a metallic layer.
 3. The battery of claim 1, whereinthe cathode comprises a cathode current collector layer and a cathodelayer and wherein the underlying layer of the cathode is the cathodecurrent collector layer.
 4. The battery of claim 1, wherein the sealingmaterial is a hot melt adhesive.
 5. The battery of claim 1, wherein thesealing material comprises a polymer selected from the group consistingof acrylics, ethylene acrylic acid (EAA) copolymers, ethylene and ethylacrylate (EEA) copolymers, ethylene methacrylic acid (EMA) copolymers,ethylene vinyl acetate (EVA) copolymers, polymethyl acrylate (PMA),acrylonitrite, vinyl chloride polypropylene (VCPP) copolymers, acrylicnitrile-butadiene-styrene (ABS) copolymers, polyethylene (PE),polypropylene (PP) and mixtures thereof.
 6. The battery of claim 1,wherein the anode and cathode tabs extend beyond the upper packagingmaterial.
 7. The battery of claim 1, wherein an outer portion of thelower packaging material extends beyond the seal area and wherein theanode and cathode tabs extend beyond the seal area and are supported bythe outer portion of the lower packaging material.
 8. The battery ofclaim 1, wherein the multi-layer dielectric sealing film furthercomprises a second layer of sealing material, wherein the first andsecond layers of sealing material sandwich the layer of dielectricmaterial.
 9. The battery of claim 1, wherein the battery cell is planarand rectangular.
 10. The battery of claim 1, wherein the current anodeand cathode tabs are planar and rectangular.
 11. The battery of claim 1,wherein the cell is rectangular with two length sides having a firstlength and two width sides having a second length wherein the anode andcathode tabs extend from one width side of the cell.
 12. The battery ofclaim 1, wherein the cell is rectangular with two length sides and twowidth sides and the anode and cathode tabs extend from one length sideof the cell.
 13. The method of claim 1, wherein the first layer ofsealing material is in contact with the anode tab and/or the cathodetab.
 14. A method of packaging a battery, the battery comprising: ananode, a cathode and an electrolyte between the anode and cathodeforming a battery cell having a periphery; an anode tab comprising afirst portion in electrical contact with the anode and a second portionextending beyond the periphery of the cell and/or a cathode tabcomprising a first portion in electrical contact with the cathode and asecond portion extending beyond the periphery of the cell; an upperpackaging layer and a lower packaging layer surrounding the batterycell, wherein the upper and lower packaging layers are sealed togetherto form a seal area outside the periphery of the battery cell andwherein one or both of the anode and cathode tabs extend between theupper and lower packaging material in the seal area; the methodcomprising: placing a multi-layer dielectric sealing film on the anodetab and/or cathode tab in the seal area, wherein the multi-layerdielectric sealing film comprises a layer of dielectric material and afirst layer of sealing material; sealing the upper and lower packagingmaterials together, wherein the multi-layer dielectric sealing film issealed between the anode and cathode tabs and the upper packagingmaterial in the seal area.
 15. The method of claim 14, wherein the upperpackaging material comprises a metallic layer.
 16. The method of claim14, wherein the cathode comprises a cathode current collector layer anda cathode layer and wherein the underlying layer of the cathode is thecathode current collector layer.
 17. The method of claim 14, wherein thesealing material is a hot melt adhesive.
 18. The method of claim 14,wherein the sealing material comprises a polymer selected from the groupconsisting of acrylics, ethylene acrylic acid (EAA) copolymers, ethyleneand ethyl acrylate (EEA) copolymers, ethylene methacrylic acid (EMA)copolymers, ethylene vinyl acetate (EVA) copolymers, polymethyl acrylate(PMA), acrylonitrite, vinyl chloride polypropylene (VCPP) copolymers,acrylic nitrile-butadiene-styrene (ABS) copolymers, polyethylene (PE),polypropylene (PP) and mixtures thereof.
 19. The method of claim 14,wherein the anode and cathode tabs extend beyond the upper packagingmaterial.
 20. The method of claim 14, wherein an outer portion of thelower packaging material extends beyond the seal area and wherein theanode and cathode tabs extend beyond the seal area and are supported bythe outer portion of the lower packaging material.
 21. The method ofclaim 14, wherein the multi-layer dielectric sealing film furthercomprises a second layer of sealing material, wherein the first andsecond layers of sealing material sandwich the layer of dielectricmaterial.
 22. The method of claim 14, wherein the battery cell is planarand rectangular.
 23. The method of claim 14, wherein the current anodeand cathode tabs are planar and rectangular.
 24. The method of claim 14,wherein the cell is rectangular with two length sides having a firstlength and two width sides having a second length wherein the anode andcathode tabs extend from one width side of the cell.
 25. The method ofclaim 14, wherein the cell is rectangular with two length sides and twowidth sides and the anode and cathode tabs extend from one length sideof the cell.
 26. The method of claim 14, wherein the first layer ofsealing material is in contact with the anode tab and/or the cathodetab.
 27. The battery of claim 1, wherein the dielectric materialcomprises a polymer selected from the group consisting of polyester(PET) or polyetheretherketone (PEEK), acrylonitrite (polyacrylonitrile),vinyl chloride (PVC), polypropylene copolymers, acrylicnitrile-butadiene-styrene (ABS) copolymers, polyethylene (PE) andpolypropylene (PP).
 28. The method of claim 14, wherein the dielectricmaterial comprises a polymer selected from the group consisting ofpolyester (PET) or polyetheretherketone (PEEK), acrylonitrite(polyacrylonitrile), vinyl chloride (PVC), polypropylene copolymers,acrylic nitrile-butadiene-styrene (ABS) copolymers, polyethylene (PE)and polypropylene (PP).